Automatic laboratory interventions to unmask and treat hypomagnesemia in the Emergency Department

The significance of hypomagnesemia and the need for treatment are under-recognized in clinical practice. Our objective was to design, establish, and test two interventions to screen for patients with hypomagnesemia and increase the rate of treatment of hypomagnesemia in the Emergency Department (ED).

A prospective two-year study was conducted. The Laboratory Information System was set to automatically order plasma magnesium in ED patients with plasma calcium < 7.5 mg/dL (1.9 mmol/L) and/or plasma potassium < 2.5 mEq/L (2.5 mmol/L). We counted the number of identified cases of hypomagnesemia, and calculated the total economic cost per identified patient. The study had three periods "Central lab" "Stat lab" and "Stat lab with comment" according to the availability to measure plasma magnesium levels in the stat laboratory and the inclusion of an automatic comment in the laboratory report in cases of hypomagnesemia. We retrospectively reviewed the medical records of patients with magnesium < 1.5 mg/dL (0.6 mmol/L), to investigate whether they have been appropriately treated.

A total of 410 plasma magnesium were measured due to our intervention; 179 due to hypokalemia and 231 due to hypocalcemia. Two hundred thirty (56.1%) of 410 showed hypomagnesemia. Each detected case resulted in reagent cost of 0.7$, when prompted by hypocalcemia, and 0.6$ when prompted by hypokalemia. The rate of patients with hypomagnesemia that were appropriately treated increased from 15% to 75% along the study period.

Our strategies successfully identified patients with hypomagnesemia in the ED at a very affordable cost, and increased the percentage of patients with hypomagnesemia that received treatment.